Machine for chill-casting under hydrostatic pressure

ABSTRACT

A machine for chill casting under hydrostatic pressure which includes a holding furnace mounted on a supporting frame including a crucible having a pouring opening in the bottom wall and a stopper mounted for movement between opening and closing positions with respect to said opening, a casting mold formed of at least two parts mounted on a rigid frame and a mold-pouring device in which the latter is formed of female and male injection nozzles one of which is mounted on the pouring jet and the other of which is fixed to the pouring hole of the furnace crucible with means for displacement of the mold to engage the male and female nozzle members.

Assignees Priority 7 United States Patent Inventors Rene Lauzier;

7 Jean Gabjllon, both of Ruy, France App]. No. 34,018 Filed May 4, 1970 Patented Aug. 17, 1971 Complgnie Pechlney Paris,; I Etahllssements Lauzier Bourgoin, France, part interest to each May 6, 1969 France 6,914,447

MACHINE FOR CHILL-CASTING UNDER HYDRQSIATIC PRESSURE 4 Claims, 5 Drawing Figs.

' US. Cl. 164/337, 164/342, 249/137 Int. Cl 33/02, ,B22d 37/00 Field of Search 164/337, 335, 342, 343, 344; 249/137 References Cited Primary ExaminerRobert D. Baldwin AnomeyMcDougall, Hersh & Scott j ABSTRACT: A machine for chill casting under hydrostatic 7 pressure which includes a holding furnace mounted on a supporting frame including a crucible having a pouring opening in the bottom .wall and a stopper mounted for movement between opening and closing positions with respect to said opening, a casting mold formed of at least two parts mounted on a rigid frame and a mold-pouring device in which the latter is formed of female and male injection nozzles one of which is mounted on the pouring jet and the other of which is fixed to the pouring hole of the furnace crucible with means for displacement of the mold to engage the male and female nozzle members.

I/ III PATENTEU M181 7 MI SHEET 2 or 3 FIG. 2

FIG. 3

INVENTOR.

PATENTED 11131 71911 SHEET 3 UF 3 FIG. 4

126 A 1232 f 1253 1 I 1251 Q L.! 1

INVENTOR.

MACHINE FOR CHILL-CASTING UNDER HYDROSTA'IIC PRESSURE pression or' cavity of a permanent mold, referred to as a chill mold, is filled manually by means of a ladle having a capacity which is substantially equal to the volume of molten material which is to be supplied. Because of the shape and its emptying possibilities, the chill mold makes it possible to obtain an article of the required shape and dimension upon solidification of the cast molten metal. I

This process requires a pouring jet having a relatively high passage for supplying the molten material to the chill mold in a manner to obtain a hydrostatic pressure for the introduction of the molten material and headers 'or feeders having liquid reserves over and above that of the article to be obtained and designed to ensure the supply of the relatively large masses of the operator; and finally the use of relatively-small hydrostatic pressure in order to ensure a suitable solidification and filling of all parts of the article.

This process is improved first by eliminating the manual factorsby automation of the operation such as pouring, mold emptying, regulation of the temperature of the chill mold and molten material, coating of the mold when necessary and by the use of molds having multiple cavities thereby making it possible to obtain a number of identical or different objects in a singleoperation, and secondly, by increasing the hydrostatic load to enhance the development of solid parts of the article by reason of the relatively high'pressure applied to the liquid phase at least until the start of solidification.

'In accordance with a first known process, a crucible containing the molten material is covered by a tight cover on which the chill mold rests. The supply channel for the chill mold is connected to a tube that is immersed in the molten material. The application of gas pressure to the surface of the molten material will cause the molten material to rise in the tube for flow to the cavities of the chill mold. The maintenance of the pressure until solidification of the metal provides for proper filling of the impressions or cavities and minimizes the need for headers or feeders which are essential to conventional molding by gravity. As soon as the solidification occurs, 'the gas pressure is discontinued and excess cause difiiculties in emptying the mold.or variations in the dimensions of the molded articles.

In accordance with a second known process, the furnace comprises a crucible which is closed at its upper end and has 'a lateral spout on which the chill mold, with its pouring system, is fixed. The furnace-crucible assembly is capable of being rocked between raised and lowered positions. In the raised position, the chill mold is at a level above the level of the molten material. When the chill mold is rocked below this level, the metal penetrates into the impression or cavity under a hydrostatic pressure which is a function of the inclination of the furnace and of the metal charge. The fusible material is supplied to the crucible through a closable opening in the material contained in the tube is allowed to flow back into the crucible.

This process has the disadvantage of requiring a fluidtight furnace which can take the pressure and consumption of a volume of gas which is proportional to the volume of the furnace which is not occupied by the molten material. The molten material can be altered by contact with the gas, such as oxidation in the case of air, with the possible formation of solid skins with consequent danger of clogging the pouring passages and providing undesirable inclusions in the molded article. Furthermore, the recharging of the furnace necessitates the removal of the cover and discontinuance of the operation of the apparatus. Finally, the portion of the chill mold in contact with the furnace cover is at higher temperature than the remainder whereby it becomes necessary to equalize the temperatures by cooling of one portion or heating of another in order to avoid abnormal deformations of joints which might upper portion of the furnace.

The temperatures'of the two portions of the chill mold are not equal and represents one disadvantage. In addition, the molten material is agitated during rocking movement with the result that turbulence and possible oxidation of material exists. Finally, the hydrostatic pressure varies as a function of the charge in the crucible.

According to a third known process, use is made of a furnace having a rod-type closure member, referred to as a stopper," which permits the pouring opening for the molten material to be closed. The chill mold, by horizontal displacement, comes into pouring position beneath the opening and filling is effected 'by lifting the stopper. After filling, the stopper is returned to the lowered position by a device controlled by an electrical means.

The free space between the pouring opening and the inlet to the chill mold permits entrainment of air with the resulting danger of turbulence and oxide inclusions. Moreover, the hydrostatic load ceases to be effective as soon as the chill mold is filled with the result that it becomes necessary to make use of larger feed heads. Finally, the pouring conditions vary with the height of the molten material in the crucible.

Thus, it is an object of this invention to provide a machine for pouring molten metal into metal molds under hydrostatic pressure; which avoids any alteration of the material being poured; which is capable of being charged without any interruption of the operation; and which enables a moderate and uniform heating of the different portions of the mold.

These and other objects and advantages of this invention will hereinafter appear and, for purposes of illustration, but not of limitation, an embodiment of the invention is shown in the accompanying drawings, in which:

FIG. 1 is a sectional elevational view of a casting machine embodying the features of this invention taken along the line I-lofFIG. 2; I

FIG. 2 is a top plan view of the casting machine embodying the features of this invention;

FIG. 3 is a sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a sectional elevational view of the crucible or pot of the holding furnace; and

FIG. 5 is a plan view of the crucible of FIG. 4.

In accordance with the practice of this invention, the machine comprises a holding furnace mounted on a supporting frame and which includes a crucible, the bottom of which has a vertically disposed pouring opening and a stopper capable of closing the pouring opening; a casting mold formed of at least two parts mounted on a movable rigid frame and a mold pouring device. The machine is characterized by a pouring device for the mold comprising a female or male injection nozzle fixed on the pouring jet, and a male or female injection nozzle capable of cooperating with the aforementioned nozzle and fixed on the pouring hole of the furnace crucible and a pressure-applying member which operates to move the mold in the direction of the crucible so that the male and female nozzles are applied against one another.

In a preferred embodiment, the pressure-applyingmember acts on the rigid frame carrying the chill mold mounted for movement about a substantially horizontally disposed rocking shaft between a pouring position, in which the pressure-applying member brings the two nozzle portions one against the other, and a mold-emptying position in which the pressure-applying member maintains the chill mold support in raised position. 1

Referring now to the drawings, the machine which is described by way of example operates to produce articles from aluminum or an alloy of aluminum by molding in a metal chill mold.'It can also be used satisfactorily for molding other metals or alloys having a melting point which can reach 1,500 C.

it comprises a mold furnace 1, a chillmold 23,24 and its support 2 and pouring means 3.

The holding furnace l is mounted on a supporting frame which includes an external casing 1 1, outside of which there is provided the support 13 for a stopper rod 12 and which contains a refractory lining 14 having a burner opening 141 through the lower portion and a rectangular chimney 18 connected with the upperportion. A burner 17 is mounted in the burner opening 141. The lining l4 defines a central space 142 that is partially occupied by a crucible or pot 15. The casing 11 is closed at its upper end by an annular cover 16 which clamps the crucible about its upper edge. The crucible is covered by a cover member 152 formed with a central opening 1521 for the passage of the stopper rod 12 therethrough. The lower portion of the crucible is equipped-with a pouring device comprising a rotating or sliding plug which is automatically controlled and permits the quantity of metal necessary for supplying the mold to be measured. As shown in FIG. 4, this device comprises a base 54 of the crucible formed with a pouring passage 151 occupied by a refractory member 153 having a vertical duct 1532 for the flow-of molten material. At its upper end, the duct terminates with a closure seat 1531 and at its lower end portion it terminates at the pouring device 3.

The stopper 12 is in the form of a hollow rod 121, the hollow portion of which can be occupied by a thermometer, such as a pyrometer rod 1212. The lower portion of the hollow rod 121 is provided with a closure valve member 1211 capable of cooperating with the seat 1531. The opening of the valve member 1211 can be effected by various mechanical or electromagnetic means, permitting a vertical movement of the closure operation and a rotary movement for sealing engagement with the seat 1531 to be simultaneously achieved. In the illustrated example, a stop 122, which can be adjusted by operation of nut member 1221, is in position to be engaged by the upper end portion of rod 121 to limit its vertical movement. The control of the vertical movement of the rod is effected by means of a device such as a bellcrank lever 123 having one arm 1231 pivoted at its end on the upper portion of the rod 12. The other end 1232 of the lever is pivotally connected to a movable member 1241 ofajack 124. The fixed member 1242 of the jack is connected at 1252 to a second lever 125 pivoted at 1251 on the support 13 carrying the control-mechanismof the stopper. A free end 1253 of the lever is connected to a resilient means 126, while the other free end 1252 is connected by a rod 1271 to a lever 1272 for rotation of the rod 121.

The stopper operates as follows: in the'open position of the closure member, the jack 124 has its rod retracted and the hollow rod 121 is raised by the bellcrank lever 123. In order to close the closure member, the jack 124 is operated in the manner to displace the rod outwardly so that the hollow rod 121 is moved by the bellcrank lever 123 until the valve member 1211 is positioned on the seat 1531. At this time, the jack 124, which continues to operate, pushes back its movable member thereby to act on the lever 125 with the result that the point 1252 is moved back to bring the resilient member 126 under tension and cause the rotation of the lever 125 in response to action by the rod 1271. This causes rotation of the lever 1272 and rotation of the rod 121, the result of which is the rotation of the valve member 1211 on the seat 1531 to effect sealing engagement of the closure member onto the seat.

The assembly 2 of the chill mold and its support comprises a movable shaft 21 on which a rigid frame 22 supporting the chill mold, which comprises a fixed part'23 and at least one movable part 24, is mounted for rocking'movement.

The shaft 21, which can be rotated, is able to turn in two bearings 211 and 212 fixed to the supporting frame 10 of the holding furnace 1. The rigid frame 22 comprisesfour rods 221 to 224 connected, at one of their ends, to a plate 225 which is fixed with the shaft 21 by means of two square portions 2251 and 2252. At their other ends, the four rods can be connected,

. either by another plate (not shown) similar to the. plate 225 or by the fixed part 23 of the chill mold.

This latter part comprises a half-impression 231 and a pouring half-jet 232, and is mounted on the four rods 221 to 224.

The movable part 24 of the chill mold comprises a half-im pression 241 and a pouring half-jet 242. Four bores 243 to 246 permit it to slide on the four rods 221 to 224. These latter also carry a knuckle joint for the displacement of the movable part 24, which comprises two rods 2471 and 2472 pivoted to one another, the rod 2471 and the rod 2472 being on the other hand respectively pivoted on the movable part 24 of the chill mold and on the rigid frame 22. The rod 2472 is also pivoted, at an intermediate'point, on a third rod 2473 which is also pivoted on the rod 2481 of a jack 248, the body of which is fast with the frame 22. The knuckle joint is preferably mounted in duplicate.

The frame is able to rock about the movable shaft 21 because of a mechanism comprising a pinion 213 keyed to the I on the rigid frame 22, serves to maintain this latter in its two extreme positions. It is not brought under pressure during the rocking movement.

The rigid frame 22 also carries the hydraulic means inherent in the movable elements of the chill mold, such as pin displacement devices and ejectors.

The pouring means 3 ensures a tight connection between the pouring jet 232 and the supply passage 312.1n the illustrated example, it is formed by a plate 31 fast with the bottom of the crucible or connected to this latter by adhesive or any other means. This plate is formed with a vertical bore 311 occupied by a refractory tubular conduit 312, disposed in the extension of the lower end 1533 of the member 153, and a nozzle holder 32 stuck in'the bottom end of the bore 311 and carrying a male conical joint capable of receiving, by welding, the upper end of the male injection nozzle 33'kept at a temperature sufficient to avoid any danger of clogging due to solidification by means of an electrical heating apparatus (not shown) or by an annular burner 34 also fixed to the chill mold, a female injectionnozzle fitting the shape of the male injection nozzle 33. This female injection nozzle, which communicates with the pouring. jet, comprises two half-nozzles 351 and 352, one fitting into the fixed part 23 and the other into the movable part 24 of the chill mold. A tank 36 permits recovery of the drops of mold material which could escape from the nozzles after they are separated. I

The operation ofthe machine is hereinafter explained:

In the initial position, the chill mold is open,.in the moldemptying position, (shown in full lines, FIGS. 1 and 2). The jack 2l5 is in the position with its rod retracted and the jack 216 is under pressure, maintaining the rigid frame 22 in the top mold-emptying position, and the jack 248 is in the position with the rod retracted. In order to carry out the molding operation, the jack 248 is brought under pressure; this causes the closure of the chill mold, and the jack 216 to be brought under atmospheric pressure so that it no longer holds the frame 22 in the top position. To bring the chill mold into position, the ejected rod of the jack 215 is displaced causing the rocking movement of the-rigid frame and the bringing of the chill mold into the pouring position, represented by broken lines in FIG. 1 and full lines in FIG. 4. The jack 216 is again brought under pressure, this ensuring the contact pressure between the chill mold and the injection nozzle 33, and the stopper 12 is opened by retraction of the rod of the jack 124. The operation of the stopper rod has been explained above. The molten material penetrates into the chill mold. When the prescribed molding time has elapsed, the jack 124 is returned to the position with its rod extended, the jack 216 is again brought under atmospheric pressure, thereby interrupting the pressure exerted by the chill mold on the nozzle 33, the rod of the jack 215 is retracted, causing a rocking movement, and then the jack 216 is again brought under pressure, so that the frame 22 is maintained in the top mold-emptying position; finally, the rod of the jack 248 is withdrawn, this causing the retraction of the upper part 24 of the chill mold'and thus the emptying 'of the mold.

All these operations are controlled automatically in accordance with a preestablished cycle, depending on the cast elements which are to be obtained. The equipment for making the operation automatic is well known and has not been described.

The supply to the holding furnace 1 is assured by a melting furnace (not shown), although the channel 41 thereof can be seen in FIG. 1.

Numerous modifications are possible. Thus the injection nozzle 351,352 can be provided on one of the two parts, fixed or movable, of the chill mold, without being separated into two parts. Obviously, it remains connected to the pouring jet 232,242. The chill mold can comprise a fixed part and several movable parts. It is then sufficient to provide as many jacks 248 as there are movable parts, or even to control at least two of these parts by a single jack by coupling them mechanically. In particular, it is possible to provide av fixed part placed between two movable parts; the free ends of the rods 221 to 224 are then preferably provided with a second plate similar to 225; the female injection nozzle of the chill mold is, if possible, fitted into the central fixed part of this latter.

The means which are used have the advantage of completely freeing the space contained beneath the crucible 15. This makes possible the use of several assemblies 2 each formed by a mold 23,24, its supporting frame 22 and its rocking mechanisms.

It is also advantageous for the mold, at the time of emptying, to be in a position which is reversed relative to its pouring position. The result then is that, at the time of emptying the mold, the molded article falls onto an element coming from the mold-pouring duct, this being an element which must in any case be removed. If this reversal had not taken place, there would be the danger of one of the useful elements of the molded article being broken by shock.

This machine permits the manufacture on a large scale of very varied objects: gas burners, door handles, cocks and fittings, ski-fixing means, hooks, cycle brakes, pivot joints for sunshades, toys.

We claim:

1. A machine for pouring molten material into a metal mold under hydrostatic pressure comprising a supporting frame, a.

holding furnace mounted on the supporting frame and having a crucible with a pouring hole through the bottom wall and a stopper mounted for movement between open and closed positions with respect to said opening, a frame mounted for movement between pouring position and retracted mold-emptying position, a casting mold formed of at least two parts mounted on said movable frame, means for relatively moving said two parts to close and open the mold, a mold-pouring device comprising a female and male ejection nozzle one of which is fixed to the pouring jet of the mold and the other of which is fixed on the pouring opening of the crucible, and a pressure-applying device for applying the mold to the nozzle of the crucible, said rigid frame being mounted for pivotal movement between said pouring position and mold-emptying position about a horizontal shaft.

2. A machine as claimed in claim 1 in which the pressureapplying device comprises a jack operatively engaging the mold for displacing the mold between pouring position and mold-empt ing position.

3. A mac inc as claimed in claim 1 in which the shaft, in the mold-emptying position, is situated beneath the frame.

4. A machine as claimed in claim 1 which includes a gear mounted on the horizontal shaft and a rack mounted on the movable member of the jack in operative engagement with the gear. 

1. A machine for pouring molten material into a metal mold under hydrostatic pressure comprising a supporting frame, a holding furnace mounted on the supporting frame and having a crucible with a pouring hole through the bottom wall and a stopper mounted for movement between open and closed positions with respect to said opening, a frame mounted for movement between pouring position and retracted mold-emptying position, a casting mold formed of at least two parts mounted on said movable frame, means for relatively moving said two parts to close and open the mold, a mold-pouring device comprising a female and male ejection nozzle one of which is fixed to the pouring jet of the mold and the other of which is fixed on the pouring opening of the crucible, and a pressure-applying device for applying the mold to the nozzle of the crucible, said rigid frame being mounted for pivotal movement between said pouring position and mold-emptying position about a horizontal shaft.
 2. A machine as claimed in claim 1 in which the pressure-applying device comprises a jack operatively engaging the mold for displacing the mold between pouring position and mold-emptying position.
 3. A machine as claimed in claim 1 in which the shaft, in the mold-emptying position, is situated beneath the frame.
 4. A machine as claimed in claim 1 which includes a gear mounted on the horizontal shaft and a rack mounted on the movable member of the jack in operative engagement with the gear. 